1. Field of the Invention
This invention relates to a substrate processing apparatus and, more particularly, to an apparatus having substrate processing chambers at different vertical levels on a transport chamber.
2. Prior Art
Mattson Technology has a system known as its ASPEN system that moves two semi-conductor wafers into and out of a process chamber at the same time. Batch systems, single wafer systems and cluster tool systems are also known in the prior art. U.S. Pat. No. 4,951,601 discloses a substrate processing apparatus with multiple processing chambers and a substrate transport apparatus. U.S. Pat. No. 5,180,276 discloses a substrate transport apparatus with two substrate holders. U.S. Pat. No. 5,270,600 discloses a coaxial drive shaft assembly of a substrate transport apparatus. U.S. Pat. No. 4,094,722 discloses a rotatable palette that holds four wafers. U.S. Pat. No. 4,381,965 discloses a multi-planar electrode plasma etcher. U.S. Pat. No. 4,675,096 discloses a take-in-and-out chamber with side-by-side take-in and take-out positions. Other related art includes the following:
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